A conventional drum type washing and drying machine includes a cylindrical rotary drum disposed in a water tub, wherein its rotational axis is horizontal or slanted with respect to the horizontal direction. The cylindrical rotary drum having a bottom surface is provided on its cylindrical surface with multiple drum perforations for allowing water and air to pass therethrough and is driven to rotate. Further, formed at a front side of the water tub is a laundry loading/unloading opening, which is opened and closed with a door. After loading laundry in the rotary drum through the laundry loading/unloading opening, washing, rinsing and water-extracting processes are performed by controlling water supply into the water tub and water drain therefrom and also by controlling the rotation of the rotary drum.
Moreover, by forming an air circulation channel for exhausting air from the water tub, running thus exhausted air through a dehumidification unit and a heating unit and re-circulating thus dehumidified and heated air back into the water tub, a drying process for drying laundry accommodated in the rotary drum can be performed. In such a way, the drum type washing and drying machine is capable of executing the drying process in addition to the washing, the rinsing and the water-extracting process. Detergent can be added into a detergent dispenser prior to starting the operation of the drum type washing and drying machine and a control panel can be manipulated as needed to set up a desired operation process of the washing and drying machine, start or temporarily pause the operation, and find out the operation status thereof.
In the drum type washing and drying machine having the above-described configuration, a lint trap filter for filtering, e.g., lint produced from laundry during the drying process is installed in the air circulation channel in order to prevent the lint from being accumulated in the air circulation channel or in a fan. The lint trap filter is configured to be attached to or detached from the drum type washing and drying machine by opening a lid plate provided on a top surface of a main body of the drum type washing and drying machine so that the lint collected in the lint trap filter can be removed at any time. By removing the lint, deterioration of air flow efficiency can be prevented (see, for example, Japanese Patent Laid-open Application No. 2000-093697).
Moreover, the lint trap filter for filtering, e.g., lint produced during the drying process includes a first filter disposed at a warm air input side and having a bag-shaped portion whose warm air input side is opened; and a plane-shaped second filter disposed at a warm air output side. For example, lint of a relatively large size produced from laundry is filtered by the bag-shaped portion of the first filter while dust of a minute size is collected in the second filter (see, for example, Japanese Patent Laid-open Application No. 2001-300192).
For such a conventional structure of the lint trap filter, however, it frequently happens that a user operates the drum type washing and drying machine without mounting one of the two filters of the dual system to a main body of the drum type washing and drying machine. In such a case, lint would be accumulated in the air circulation channel or in a fan, resulting in deterioration in air flow efficiency and drying efficiency.
Furthermore, the conventional lint trap filter disclosed in Japanese Patent Laid-open Application No. 2001-300192 is disadvantageous in that the two filters are installed separately and the attachment thereof is somewhat troublesome.